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Abstract

Although many life-history traits are inflexible, extrinsic factors are likely responsible for variation in attributes such as growth rates and ultimately adult body size. Nutritional stress during natal periods, in particular, has significant long-term consequences for adult characteristics. It is thought that poor natal nutrition leads to either the diversion of subsequent energy intake into compensatory growth or delayed maturation. Diversion of energy, to achieve compensation, however does not come without consequence; immune defense is a resource-demanding activity, which can trade- off with traits such as growth. Relatively little is known about the intra- or interspecific variation in immunological capabilities, especially in the context of the effects of stress on immune function. Stress induced levels of glucocorticoids (corticosterone) cause a shift in physiological parameters such that self-maintenance and survival processes are prioritized; by redirecting resources, corticosterone and thus stress especially at chronic levels is generally considered immunosuppressive. I looked at the effects of poor natal nutrition and the potential for compensation on types of immune defense and corticosterone levels in checkered garter and corn snakes, species with different sexual dimorphisms. The effects of accelerated growth rates, following a period of suppressed growth, on immunological function and stress were negligible. This suggests that either snakes are robust animals that can maintain health at low levels of food intake, or that immune function parameters are not downgraded when excess energy is allocated towards compensation (partial or complete). Immune function is thus suggested to be evolutionarily adapted to be maintained during periods of stress.